Never came up when he was younger, although there were plenty of gaffs by Joe in those years.  And there were loads of times his judgement & political views as well as his gaffs were under scrutiny in his 8 yrs as VP..

Oh now I get it -- a new defense asserted by today's  media. -- Might come in handy these days to divert critics.  

Of course his adversaries may allege a different aliment like alzheimer's.